This is one of those things that is likely to take forever to be accepted, because native English speakers will pretty consistently say that "a hot tea" sounds wrong (which it almost always does), and some will even be able to explain the rule for why it sounds wrong, which is that tea is an uncountable noun (cup is countable, so "a cup of tea" works), and the indefinite article cannot be used for uncountable nouns. And that's a pretty solid case against accepting it. However, almost anything will become countable as a menu item, at least in informal speech, so if you're comparing menu items, you could still make the case for accepting "a hot tea" with "a cold tea." (However, if you refer to "a hot tea" but just "cold tea" rather than "a cold tea" then it sounds like the cold tea is not a menu item--not that "a" is required for menu items, but it is weird to use it inconsistently for menu items--and so it sounds like you're making a comparison that doesn't make sense, between a hot tea from McDonalds and cold tea from the grocery store or something. So, if you only put "a" at the beginning but not before "cold tea" than I still wouldn't accept it.) Note: everything I said was as an American, and may not be the same in other dialects of English.